It appears Red Hat fixed this problem with a kernel patch in RHEL 7.5 that was not upstreamed.
https://access.redhat.com/errata/RHSA-2018:1062
BZ - 1471875 - soft lockups during unmount when dentry cache is very large
https://bugzilla.redhat.com/show_bug.cgi?id=1471875
It appears Red Hat fixed this problem with a kernel patch in RHEL 7.5 that was not upstreamed.
https:/ /access. redhat. com/errata/ RHSA-2018: 1062
BZ - 1471875 - soft lockups during unmount when dentry cache is very large
https:/ /bugzilla. redhat. com/show_ bug.cgi? id=1471875